Wireless systems use a variety of methods to establish and maintain communications between devices. In wireless local area network (“WLAN”) systems, communications is typically between a fixed access point (“AP”) and a mobile station (“MS”), as illustrated in FIG. 1. As the distance increases between the AP and an MS, the physical layer coding rate is adjusted to ensure that wireless messages are received properly.
A class of coding methods which have been developed to help ensure that wireless messages are received properly over longer ranges are turbocodes. Turbocoded messages are different than non-turbocoded messages in that for turbocoded messages, the bits of the original message are convoluted and otherwise operated upon to help ensure their successful reception and subsequent processing. A result of these operations is that the receiving device needs to receive the entire message prior to processing any portion of the message, i.e., to perform the reverse operations to get back to the original message. Additionally, processing turbocoded messages is an iterative process, which means that the message must be operated upon multiple times to get back to the original message. This also takes additional time.
For non-turbocoded messages, each bit can be processed upon reception. Due to this difference between turbocoded messages and non-turbocoded messages, it takes longer for a receiving MS or AP to determine the integrity of a turbocoded message, and subsequently it takes longer for a receiving MS or AP to reply to a turbocoded message.
This is a problem, as the timing structure for acknowledgements on a communication system, such as a WLAN system, specifically an 802.11 system, is fixed, and the time allowed for responses (acknowledgements) from the receiver to the sender of the message is short. Specifically, the time allowed for the acknowledgements is shorter than the time to process a turbocoded message.
Thus, there exists a need for a method to transmit and process delayed acknowledgements for messages that require additional processing time.